This invention relates to providing an article for absorbing body fluids. More particularly, this invention relates to an absorbent pad for use in products such as sanitary napkins, panty liners, diapers and the like.
In general, such products comprise one or more layers of a core of hydrophilic material such as wood pulp, rayon, tissue or the like. The hydrophilic material, generally fibrous in form, is provided as a pad having a rectangular or oblong shape or, in some cases, a shape designed to fit the anatomy of the wearer more closely. Such products may also be designed to have wings or flaps, which extend transversely from the product and serve to protect the wearer's panty from becoming stained due to the tendency for body fluid to flow over the sides of the napkin. The pad is usually provided with an enveloping cover pervious to body fluids on the side of the pad which is to be placed against the body and impervious to such fluids on the side facing away from the body. The object of such a body fluid impervious cover is, of course, to protect the wearer's clothing from staining and wetting.
In general, such products have satisfactorily performed their function of absorbing and retaining body fluids and preventing staining and wetting of the wearer's clothing. When the product is properly placed and retained by the wearer in its intended position, bodyfluid is directed at or near the center of the product and distributes, by means of liquid wicking, radially from the point of deposition throughout the absorbent medium. However, sometimes the product is misplaced, or becomes saturated with use. Further, the width of the product is generally much smaller compared to the length of the product. After striking the surface of the product, the fluid radiates approximately equally in all directions from the point of deposition. Thus, it tends to strike the longitudinal sides of the product before it travels toward the ends of the product, potentially causing staining at the sides before the full absorbent capacity of the product is utilized.
Sometimes, body fluid strikes the pad off-center and closer to the peripheral edges of the pad. If the body fluid strikes the pad off-center, the fluid tends to wick toward the side closest to which the fluids struck the pad and cause a failure, i.e., the staining and wetting of the clothing of the wearer by body fluid. Such failures are known as "side failures".
There have been efforts in the past to direct the flow of fluid in a longitudinal direction in order to provide means to saturate the napkin longitudinally, rather than laterally. For example, U.S. Pat. No. 4,524,474 (Svensson) describes an absorption pad for protecting a bed which includes a lower liquid impervious material layer and an upper liquid absorbent material layer laminated to the lower layer. The liquid absorbent layer is impregnated with strings or filaments of a liquid-resistant agent which does not stiffen the pad. The strings form a grid-like pattern for defining compartments between the strings over the entire area of the absorption pad. However, a grid-like pattern would not be effective in a sanitary napkin or like product because such a pattern would not effect a longitudinal saturation without aiding a lateral saturation. Furthermore, strings or filaments would not prevent excessive seepage throughout the absorbent material.
Canadian Patent No. 803,531 (Ruffo) describes a pad having a moisture-proof wrapper which is corrugated into a series of alternate, parallel ridges and grooves extending lengthwise of the napkin. This moisture-proof wrapper is placed beneath the absorbent layer and acts as a series of troughs to guide the body fluid along the longitudinal axis. However, this moisture-proof wrapper appears only at the bottom of a fibrous absorbent layer, thus allowing the body fluid to continue to flow along the transverse axis of the absorbent material and over the sides of the napkin.
U.S. Pat. No. 3,954,107 (Chesky et al.) describes an absorbent article having side portions which define a longitudinally extending channel adjacent the lateral midpoint of the pad, the side portions separating during use to expose an increased area of the pad assembly. However, this type of assembly may prove awkward during use, as it is designed to separate and fail to remain integrated. This pad is also likely to deform, which increases the probability of product failure.
It is, therefore, an object of this invention to provide an absorbent product capable of controlling and directing flow of body fluid so as to prevent failure at the sides and/or ends of the absorbent product.
Thus, it is an object of this invention to provide an absorbent product which is capable of directing body fluid to flow in longitudinal directions while substantially impeding the flow of such body fluid in transverse directions.
Another object of this invention is to provide an absorbent product which substantially prevents side failure.
It is yet another object of this invention to provide an absorbent product which may become largely saturated with body fluid without incurring side failure.
Another object of this invention is to provide a sanitary protection product which makes efficient use of the absorbent capacity of its absorbent element.
Yet another object of this invention is to provide a chambered sanitary protection product which substantially maintains its structural integrity during use.